This invention relates to a quick coupling for attaching implements to the boom of a piece of heavy equipment, and in particular to a quick coupling that permits interchangeability of implements between different pieces of equipment.
Heavy equipment having booms are detachably coupled to the implement carried by the boom to permit the use of multiple types of implements. It is common for the equipment to be connected to the implements through a hydraulically-operated quick coupling in order that the implements can be coupled and uncoupled without having to leave the machine. Prior art quick couplings have several problems, however, which limit their use.
The major problem results from the fact that the boom and the implement together form a four-bar parallelogram linkage with the top link being attached to a piston cylinder, so that when the piston cylinder is extended or retracted the implement is rotated relative to the boom. This linkage requires two axes of rotation at the implement, and the geometric relationship between these axes is critical to maintaining the full range of implement rotation. However, different manufacturers of equipment use different geometric relationships and, as a result, a quick coupling on a particular machine can only be coupled with implements having a quick coupling configured for that machine. Thus, implements are not interchangeable between machines and an operator utilizing machines, from different manufacturers must have a duplicate inventory of implements.
In addition, most prior art quick couplings couple at the two implement axes of rotation. Thus, as the coupling elements start to wear, the coupling becomes loose and control is lost. Furthermore, the coupling elements often have a relatively small contact surfaces so that wear occurs quickly and the coupling elements are prone to premature breakage.
Another problem with prior art quick couplings is that the attachment axis on the stick, that the implement rotates around, is offset from where the attachment axis would normally be located on the implement. As a result the tip radius of the implement is altered by the use of the quick coupling. This also affects operation of the machine.
Finally, when prior art quick couplings are attached to a bucket, they are attached in a manner such that they can only be coupled when the bucket is oriented open-end up. As a result, when the bucket is stored it collects rain water, which leads to rusting.
The subject invention overcomes the foregoing shortcomings and limitations of the prior art quick couplings by providing a quick coupling having a coupler element that is attached to the boom at its normal attachment axes, thereby not interfering with the preferred geometric relationship between these axes. The coupler is configured to couple with a bracket that is attached to the implement. Thus, the coupling elements is the same for every machine and implements are completely interchangeable. This result is achieved by locating the first attachment axis on the stick at the same point on the coupler for every machine, and placing the second attachment axis on the implement linkage at a different point on the coupler for every machine.
In a preferred embodiment, cylindrical bosses are located on the coupler coaxial with the first attachment axis. Receptacles are placed at the bottom of the bracket on the implement which matingly receive the bosses. A wedge located at the top of the coupler is movable in a track by actuation of a piston cylinder. The operative face of the wedge interacts with cam surfaces on the bracket such that the bracket is pulled snugly against the coupler when the wedge is moved downwardly in the track. As the bracket moves toward the coupler, overlapping surfaces on the respective elements cause the bosses to be urged downwardly into the receptacles. Thus, when the wedge is moved downwardly by the piston cylinder, the coupler and bracket are snugly joined. Since this joinder is accomplished by a double wedge, wear of the elements does not affect the tightness of the coupling. In addition, the bosses, the wedge and the mating surfaces all have large surface areas which lessen the amount of wear that does occur and provides a strong coupling. Since the implement is rotated about bosses which are coaxial with the normal first attachment axis of the stick, the tip radius of the implement is not changed by the quick coupling.
In a preferred embodiment, springs are releasably attached to the wedge to normally urge it downwardly in the track. Thus, if the hydraulic system should fail the wedge will continue to be retained and the quick coupling will not open and release the implement. In addition, the wedge is drilled to receive bolts that can be engaged in threaded bores in a plate mounted in the coupler below the track. If necessary, the wedge can be engaged manually by inserting and tightening the bolts after the piston cylinder and springs have been disconnected.
Accordingly, it is a principal object of the subject invention to provide a quick coupling for attaching implements to heavy equipment which permits complete interchangeability between implements and machines from different manufacturers.
It is a further object of the subject invention to provide such a quick coupling in which the rotational geometry of the equipment is not altered from its preferred relationship.
It is a still further object of the subject invention to provide such a quick coupling which has large contact surfaces to minimize wear and breakage.
It is a further object of the subject invention to provide such a quick coupling in which wear of the coupling elements is automatically compensated for.
It is a yet further object of the subject invention to provide such a quick coupling in which the tip radius of implements used with the coupling are not altered.
It is a further object of the subject invention to provide such a quick coupling which, when used with a bucket, allows the bucket to be coupled and uncoupled when resting open side facing down.
The foregoing and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.